You’ll need to make a CL program with the WRKUSRPRF command and change the user profile to run this program as the initial program.
You can certainly do it with a CL program, but why not just go straight to the default MAIN menu? WRKUSRPRF The command line is the same.
Better might be a CL program that prompted the CHGUSRPRF command in a loop and waited for entry of a user profile name.
No command line needed. Essentially no chance of getting off into other unrelated areas.
At worst, it could be a simple CL menu program with two or three options like a prompted CHGUSRPRF command.